The Celestia Superhighway: Supporting High Data Availability on Blockscout
Celestia is addressing the data availability problem head-on. Their DA layer is equipped to handle the massive data growth coming from new rollups and increased rollup usage. With the new Blockscout integration, data on Celestia and Celenium is easier than ever to find and explore.
Celestia is a Layer 1 (L1) blockchain specializing in processing blobs (large data batches) sent from rollup chains (L2s). Once processed, block explorers store, catalog, and present this data to users. Celenium is the native blob explorer for Celestia, but tracking data blobs as they traverse between the rollup L2 and the Celestia L1 DA layer has been an ongoing challenge.
With the new Blockscout integration, transaction visibility comes full circle. Supporting both Optimism and Arbitrum rollups, the Blockscout-Celenium update provides visibility into the large data blocks processed on Celestia’s DA layer. Blob information can be easily tracked, and connections between the Celenium blob explorer and Blockscout gives developers access to detailed blob analysis on multiple fronts.
Block explorers play a pivotal role in supporting both L2 and L1 data views as transaction data flows between the two layers. For rollups, Blockscout supports L1 <-> L2 deposits and withdrawals as well as transaction data batches posted from L2s to their L1 counterparts. Now, with Celestia support and the Celenium integration, blob data is more transparent and accessible for everyone.
- Rollups using Celestia for blob storage can now have their blob metadata surfaced directly within Blockscout.
- Cross-referenced views between Blockscout and Celestia’s Celenium explorer ensure transparency and traceability.
- Support for both Optimism and Arbitrum rollups expands usability for a wide array of chains and developers.
- Developers gain simplified access to blob and batch data through clear APIs and UIs.
- Users get greater confidence in transaction visibility and data verification.
In short, the integration brings scalable blob visibility to the forefront, solving key availability problems for rollup ecosystems and offering a developer- and user-friendly experience.
Data Availability Views
At a high level*, the new integration improves data batch visibility for rollups that use Celestia. The integration includes:
- A list of batches (blobs), sorted by recency and accessed from the Blockscout Txn Batches menu. | example
- A dedicated page for each batch with details including links to all transactions and blocks contained in the batch, the Celestia commitment and block number, the L1 transaction data, and a link to Celenium for more detailed info. | example
- The Celenium explorer features a link to the View the batch on Blockscout, providing complete explorer cross-chain coverage. | example
*detailed information on available views, API endpoints and differences between the Optimism and Arbitrum integrations is referenced later in this article.
What are Blobs?
Transaction data needs to be sent from L2 rollups to the L1 settlement layer for increased security and decentralization. It can be compressed and sent in batches, but without other optimizations this becomes difficult.
When sent from the L2 to the L1 through calldata, data processing is expensive and causes congestion on the L1. To address this issue, Ethereum introduced blobs (Binary Large Objects) with EIP-4844. This upgrade allowed for a new transaction type that could handle much larger data batches (up to 128KB in size) called blobs, which are stored on the Ethereum consensus layer for a limited timeframe.
Impact: Blobs immediately eased chain congestion and data-posting costs, however the available blobspace filled up over time and became more expensive as more rollups launched and began posting data. The recent Ethereum Pectra upgrade has once again eased congestion by allowing up to 9 blobs per block (up from 6), but it is likely that this space will also fill up with increased rollup usage.
Similar to building another lane on a highway, these upgrades provide more space which is eventually filled up by more traffic. To accommodate the ever-growing amount of rollup traffic, additional data availability solutions are needed.
Enter Celestia: A DA superhighway that can handle massive amounts of data at a very low cost.
How Celestia Works
Data Flow Process
- Rather than sending a batch of data or blob to Ethereum (or other underlying L1), L2s send blobs to Celestia, which serves as the L1 for data availability
- Blobs are added to a Celestia block
- A Celestia block can include multiple blobs from different rollups
- Each Celestia block can hold up to 8,000 KB of data per block (compared to 768 KB max per block for Ethereum post Pectra)
Verification Process
- Blocks are assembled into a unique matrix structure
- Advanced merkle proofs of that structure are included directly in the header
- Celestia Light nodes (which can run on any hardware, even a browser) only need to download the block header and small chunks of random data from the block
- Each light node takes that small sample of data and verifies it is valid
- Combined with validated samples from many other light nodes, the block data can be statistically verified
- This process works better when many light nodes to participate, improving decentralization of the protocol
Namespace Organization
Blobs sent to Celestia are paired with namespaces - an identifier that shows which rollup posted the data. This is important since Celestia blocks can include blobs from multiple rollups. Each rollup can then verify only the data that they sent to Celestia and exclude all other namespace data, making the verification process fast and efficient.
Commitment Process
Once the block is verified, data root commitments are relayed from Celestia to a smart contract on Ethereum. This commitment, signed by Celestia validators, proves that the data blobs are included and available on the Celestia blockchain.
Explorer Ecosystem
Celestia blobs are searchable via the Celenium explorer. This specialized explorer is designed for viewing blob details and storing blob contents. However, it is only available for Celestia blob data.
The new Blockscout integration adds basic Celestia blob info (commitment hash, Celestia block, etc) to the primary Blockscout block explorer while providing a link to the blob on Celenium where users can access additional details.
Celenium also links back to Blockscout so users can view batch information on the chain explorer. This cross-referencing architecture helps create visibility and transparency for Celestia blobs across multiple contexts.
Blockscout Integration
Data Flow Architecture
- Celestia Network: Produces blocks consisting of blobs sent from various sources.
- DA Indexer: Runs on top of a Celestia light client, receives and stores blob info in a dedicated database.
- Batch Fetcher: Monitors on-chain transactions and identifies relevant batch/blob transactions, requests this data from the DA indexer, and adds it into the Blockscout database.
- Blockscout DB: Stores batch/blob info in additional tables.
- Blockscout API: Serves relevant data to the Blockscout UI (and can be called independently by applications).
- Blockscout UI: Displays batch/blob data, provides link to Celenium.
- Celenium.io Explorer: Accesses routing info from the DA Indexer to provide links to Blockscout batch info.
The DA indexer service is available at https://github.com/blockscout/blockscout-rs/tree/main/da-indexer. The ReadMe includes additional information about API endpoints, parameters, and responses.
Explorer Views
Blockscout supports Celestia blobs for both Optimism-based rollups and Arbitrum-based rollups. Since the data structures vary slightly, there are different views and associated API endpoints.
Optimism Rollups
- Example rollup: Foundation network
- Block Explorer: https://foundation-network.cloud.blockscout.com/
A list of blobs can be accessed from the Blockchain > Txn Batches menu: https://foundation-network.cloud.blockscout.com/batches
Batches (blobs) are sorted from the most recent, and include the number of blocks and transaction count included in each batch. The storage type is tagged as a Celestia blob.
Clicking through the Batch ID, blocks or Txn brings you to the associated Batch page.https://foundation-network.cloud.blockscout.com/batches/14009
On the details tab you can see the Batch ID, Timestamp, transactions, blocks and the batch data container. The container includes:
- Commitment: Hash calculated during Celestia block creation and used in proof verification. More info
- Height: Celestia block number that includes this batch
- Timestamp: When the blob was committed on L1
- L1 txn hash: The hash of the commitment transaction on the associated L1 (Ethereum), that proves the blob is included and available on Celestia.
- Blob page link: A link to the Celenium explorer where you can view additional information including the raw blob data, namespace info, and the rollup id.https://celenium.io/blob?commitment=PD0n4O/LWOSgTIW8TYnnCan7sDQAi1wW5AuSh95nwd8=&hash=AAAAAAAAAAAAAAAAAAAAAAAAAN/xAxpagCrjLVQ=&height=5537559
The Celenium explorer also features a link to Blockscout to view batch information for the blob.
Blockscout Optimism API
Optimism specific endpoints are available for fetching batch information.
- General batch info including DA type, batch id and transaction counts
/api/v2/optimism/batches/api/v2/optimism/batches/count
- Specific batch info
/api/v2/optimism/batches/{internal_id}/api/v2/blocks/{block_hash_or_number}- Celestia data batch container information is included in the response/api/v2/optimism/batches/da/celestia/{height}/{commitment}
Arbitrum Rollups
- Example rollup: Rari testnet. Rari is an L3 which settles to Arbitrum L2. The Rari testnet settles to the Arbitrum Sepolia instance (which in turn settles to Ethereum Sepolia).
- Block Explorer: https://rari-testnet.cloud.blockscout.com/
A list of blobs can be accessed from the Blockchain > Txn Batches menu: https://rari-testnet.cloud.blockscout.com/batches
Batches (blobs) are sorted from the most recent, and includes finalization status, the L1 block and tx hash containing the commitment, the block and transaction count in the batch. The batch type is tagged as Celestia.
Clicking through the Batch ID or Txn count brings you to the associated Batch page (other links redirect to the settlement layer explorer, in this case Arbitrum Sepolia). https://rari-testnet.cloud.blockscout.com/batches/87433
On the details tab you can see the Batch number, Timestamp, transactions, blocks, L1 relevant information (on Arbitrum Sepolia) and the state hash before and after the batch. The Transactions and Blocks tab shows information about specific txs and blocks included in the batch.
Clicking show data availability info displays the Celestia block number and the commitment hash.
- Height: Celestia block number that includes this batch
- Commitment: Hash calculated during Celestia block creation and used in proof verification. More info
- Blob page link: A link to the Celenium explorer where you can view additional information including the raw blob data, namespace info, and the rollup id.
Blockscout Arbitrum API
Arbitrum specific endpoints are available for fetching batch information.
- General batch info including DA type, finalization status, batch number and transaction counts
/api/v2/arbitrum/batches/api/v2/arbitrum/batches/count
- Specific batch info including Celestia blob/blobs metadata such as height, namespace, and commitment, among other details.
/api/v2/arbitrum/batches/{batch_number}/api/v2/arbitrum/batches/da/celestia/{height}/{commitment}
Conclusion
As the blockchain ecosystem continues to scale, the demand for efficient data availability solutions is more important than ever. Celestia's data architecture provides the superhighway that rollups need. It is capable of handling massive data volumes at minimal cost while maintaining the security and decentralization that blockchain applications require.
The Blockscout-Celestia integration ensures that blob data is easy to find and explore in various contexts. This integration provides an important link between a chain’s primary block explorer and the Celenium blob explorer, giving users access to batch information, tools for discoverability, and storage for blob data. Support for Optimism and Arbitrum means opens access for many rollups to take advantage of this infrastructure and achieve high data availability and transparency along with a seamless explorer experience.
For developers, this means simplified workflows and reduced integration complexity. For users, it provides confidence that data is both available and accessible. And for the broader ecosystem, it represents a significant step toward a multi-layered blockchain future where specialized layers work together to support massive scalability and growth.